The high pressure forces occurring in the roller gap during the operation of such roller presses or material bed roller mills have to be absorbed by the frame of the roller press. The upper flanges of the upper frame portion are for that purpose connected by way of head pieces (pressure beams) to the lower frame portion to form a closed rigid frame.
If, after a specific operating time, the rollers of such roller presses are to be replaced or serviced, the rollers have to be removed from the frame of the roller press. The closed rigid frame of the roller press must for that purpose be opened to such an extent that the rollers with their bearing shoes can be removed through one end of the frame. Normally, this opening of the frame occurs at the end that is adjacent to the fixed roller because the pressure system for generating the roller pressure is located between the head pieces of the other end and the loose roller.
Various proposed solutions are already known for opening the frame at one end in order to mount or dismount the rollers. During that process, the head pieces of that end are removed from their operating position.
In the roller press according to DE 20 2004 001 187 U1, the head pieces can for that purpose be folded downwards about an axis of rotation which extends horizontally and parallel with the roller axis, it being possible to use them in the lower end position as rails for moving the roller units out. In the operating position, the head pieces are connected at their upper and lower end by bolts to the upper and lower frame portion, respectively. Since those bolts lie entirely within the force flow of the closed frame, they are exposed to severe stresses and have to be designed to be very sturdy. At the same time, however, those bolts are subject to a very narrow tolerance which means that manufacturing costs are high. Another disadvantage of this known embodiment is that the upper frame portion, when no longer supported by the downwardly folded head pieces, has to be held in position by additional auxiliary means.
In the roller press according to WO 2007/033800 A1, the two head pieces are, at the end of the frame that is adjacent to the fixed roller, pivotable upwards and outwards about horizontal pivot axes which extend in a cross-frame of the upper flange perpendicularly to the roller axes. The upper frame portion is held in position by a permanently mounted additional frame, which involves considerable extra cost.
A roller press, that has the head pieces, which can be removed from their operating position, can be pivoted outwards about vertically extending axes, and they continue to support the upper frame portion even in the position in which they are pivoted out is also known from practice. Additional auxiliary means for holding the upper frame portion are therefore unnecessary when the rollers are to be mounted or dismounted.
However, that known embodiment too is still encumbered with the disadvantage described above that the pivot bolts of the head pieces are subjected to severe stresses during operation and therefore have to be manufactured at the same time sturdily and with a narrow tolerance.
The object of the invention is therefore to avoid the shortcomings of the known embodiments and to develop a roller press in such a manner that inexpensive manufacture results and the mounting and dismounting of the rollers can be carried out in a time-saving and simple manner.